1. Field of the Invention
The present invention relates to a label printer for printing a given image on a label and, more particularly, to a label printer using a label sheet consisting of an elongated base sheet and a plurality of labels attached to the base sheet to issue the labels separated from the base sheet after printing the image.
2. Discussion of the Related Art
FIGS. 13 to 17 show a label printer disclosed in Japanese Utility Model Application Nos. Hei 3-98970 and Hei 3-98971 both filed by Tokyo Electric Co., Ltd., the employer of the present applicant. The label printer will be described as the related art of the present invention with reference to FIGS. 13 to 17.
As shown in FIG. 13, the label printer generally denoted by reference numeral 1 includes a body housing 2. A label printing section 3 and a sheet supplying section 4 are provided in the body housing 2 at the front and rear portions thereof, respectively. A label sheet 5 in the form of a roll is rotatably supported in the sheet supplying section 4. The label sheet 5 is unwound to be supplied from the sheet supplying section 4 through a sheet feed path A to the label printing section 3. The label printing section 3 includes a bracket 6 pivotably mounted on a pivotal shaft 6b which is supported to the body housing 2, a line head 7 supported to the bracket 6, and a platen roller 8 rotatably supported to the body housing 2. The line head 7 is adapted to separably contact the platen roller 8 through the label sheet 5. A label separating member 9 is mounted to the body housing 2 so as to extend substantially parallel to the platen roller 8 on the front side thereof.
The label sheet 5 consists of an elongated base sheet 11 and a plurality of individual labels 10 separably attached to the base sheet 11. Each label 10 is adapted to be separated from the base sheet 11 by the label separating member 9 after a given image is printed on each label 10 by the line head 7. After separating each label 10, the base sheet 11 is fed and ejected by a sheet eject unit 12. As shown in FIGS. 14A to 16, the sheet eject unit 12 includes a unit frame 13. A pair of recesses 14 are formed on the upper surface of the unit frame 13 at the laterally opposite ends thereof. A pair of bearings 16 are slidably received in the recesses 14 PG,4 through a pair of coil springs 15, respectively. A roller shaft 17a of a pinch roller 17 is rotatably supported at its opposite ends by the bearings 16. The sheet eject unit 12 further includes a U-shaped swing member 18 for displacing the pinch roller 17 with respect to the platen roller 8. The swing member 18 has a laterally extending bar portion 19 and a pair of swing arms 20 extending rearward from the bar portion 19 at the laterally opposite ends thereof in perpendicular relationship thereto. The swing arms 20 are formed at their rear ends with a pair of recesses 21 open to the upper side, respectively. The recesses 21 engage a pair of support pins 22 formed at the rear end portion of the unit frame 13 so as to project laterally outwardly. Thus, the swing member 18 is swingably supported to the unit frame 13. The lower edges of the swing arms 20 of the swing member 18 normally abut against the roller shaft 17a of the pinch roller 17. The bar portion 19 of the swing member 18 is formed in a substantially tubular configuration so as to receive a cam shaft 24. A pair of bearing holes 23 are formed at the front end portion of the unit frame 13 so as to rotatably support the cam shaft 24 at the opposite ends thereof. The cam shaft 24 received in the bar portion 19 abuts against a pair of upper edges 19a of the bar portion 19 against the biasing force of the coil springs 15 normally applied in an upward direction. The cam shaft 19 has a pair of semicircular cam portions 26 formed by cutting. The cam portions 26 engage the upper edges 19a of the bar portion 19, respectively. An operating lever 25 is connected to one end of the cam shaft 24.
As shown in FIG. 17, a pair of support frames 27 are fixedly mounted on the body housing 2. The pivotal shaft 6b is fixedly supported at its opposite ends to the support frames 27. The bracket 6 is pivotably supported to the pivotal shaft 6b. The bracket 6 and the sheet eject unit 12 are disposed between the support frames 27 in such a manner that the pinch roller 17 is adapted to separably contact the platen roller 8 from the under side thereof.
In the label printer 1 mentioned above, a given image such as commodity information is printed on each label 10 of the label sheet 5 carried on the platen roller 8 by thermal scanning of the line head 7. After printing the image, the base sheet 11 is bent at an acute angle by the label separating member 9 to separate each label 10 from the base sheet 11 and project a front half portion of the label 10 out of the body housing 2. After separating the label 10 from the base sheet 11, the base sheet 11 only is fed by the platen roller 8 and the pinch roller 17, and is ejected out of the body housing 2. In this manner, the issue of the plurality of labels 10 is continuously performed.
As mentioned above, the front half portion of each label 10 on which the image has been printed by the line head 7 is separated from the base sheet 11 and projects out of the body housing 2. Accordingly, an operator can easily draw the issued label 10 and attach it to a commodity (not shown), for example.
In setting the label sheet 5 in the label printer 1, the operating lever 25 is manually operated to rotate the cam portions 2,5 of the cam shaft 24 and thereby lower the swing member 18 engaging at the upper edges 19a of the bar portion 19 thereof with the cam portions 26 as shown in FIG. 14B. As a result, the roller shaft 17a of the pinch roller 17 engaging the swing arms 20 of the swing member 18 is lowered against the biasing force of the coil springs 15, and accordingly the pinch roller 17 is separated from the pinch roller 8. In this condition, the base sheet 11 is inserted through the space defined between the platen roller 8 and the pinch roller 17. Then, the operating lever 25 is returned to its initial position, thus setting the base sheet 11 between the platen roller 8 and the pinch roller 17 as shown in FIG. 14A.
In the label printer 1, the pinch roller 17 can be held in a contact position and a separate position with respect to the platen roller 8 by the operation of the operating lever 25. Accordingly, the label printer 1 can eliminate troublesome work in setting the label sheet 5 such that the bar portion 19 of the swing member 18 is kept lowered with an operator's hand and the base sheet 11 is then inserted through the space defined between the platen roller 8 and the pinch roller 17 with the other hand.
However, in the structure wherein the bar portion 19 of the swing member 18 is displaced by rotating the cam portions 26 of the cam shaft 24, displacement of the bar portion 19 is small, so that the pinch roller 17 cannot be largely separated from the platen roller 8. Accordingly, it is difficult to insert the base sheet 11 through the small space between the platen roller 8 and the pinch roller 17. Thus, operability in setting the label sheet 5 is hindered.
To cope with this, it may be considered to increase the displacement of the bar portion 19 of the swing member 18 by enlarging the cam portions 26, thereby increasing an amount of movement of the pinch roller 17. In this case, however, a space to be occupied by the enlarged cam portions 26 becomes large, and a large space for permitting the increased displacement is also required under the swing member 18, resulting in an increase in size of the label printer 1.